?
Do you mean how often to change it or how often should you be topping it up?
If it's the former then it depends on the service regime that the car's on. If it's on fixed servicing then change the oil every year or 10K miles whichever comes first. If it's on longlife servicing then it's when the car decides based on the condition of the oil. This can be anywhere from 9K to
30K miles. To use this service routine, you must use Longlife oil like Castrol SLX2 or any other oil that conforms to VW506.01.
If it's the latter, then that's simple. Check the oil every week and add if it's low on the dipstick! I've heard of some engines using a litre every
1-2K miles. Mine has used about 1.5litres in 17K miles.